A radio control transmitter for a model controlling an object to be controlled such as a model plane, a model helicopter, a model car or a model boat comprises a stick lever operating a main controller and various levers and switches operating as an auxiliary controller. Each of the stick lever and the various levers is connected to a shaft of a variable resistor. Each of the various switches operates as the auxiliary controller by turning ON and OFF. Each of the stick lever and the various levers is controlled to control a rotational range of the variable resistor, thereby generating multiple control signals that is transmitted from the radio control transmitter as a radio frequency wave. The object to be controlled has a receiver for receiving the control signal and servos for operating an operating section of the object to be controlled. The object is remotely controlled by controlling an operating range of each of the servos based on the control signal received by the receiver.
For instance, when a model helicopter is remotely controlled as the object to be controlled, the model helicopter including a main rotor and a tail rotor is flown with various maneuvers by operating the stick lever of the radio control transmitter for the model to control pitch angles of the two rotors (Japanese Patent Publication 2000-225277 for reference).
In other words, the control of the pitch angle of the main rotors is carried out by controlling a swash plate using the servo wherein the swash plate is disposed concentric with a shaft of the main rotor and has a degree of freedom in three axes.
FIG. 7 illustrates a control manner of the swash plate in the model helicopter (the main rotor is not shown). A control of forward and reverse shown in FIG. 7 (a) is referred to as a pitch control (also referred to as an elevator control), a control of left and right shown in FIG. 7 (b) is referred to as a roll control (also referred to as an aileron control), and a control of up and down shown in FIG. 7 (c) is referred to as a collective pitch control. The helicopter is controlled to a desired direction by combining the controls during a flight.
Specifically, in order to fly the helicopter in a forward direction (a direction of an arrow A) shown in FIG. 7(a), a left stick lever 101L of a radio control transmitter 100 is pushed upward (forward) to control a swash plate 120 disposed concentric with a shaft of a main rotor 110 using the servo (not shown) in a manner that the swash plate 120 is tilted in a direction of an arrow a. In order to fly the helicopter in a left direction (a direction of an arrow B) shown in FIG. 7(b), the left stick lever 101L of the radio control transmitter 100 is pushed left to control the swash plate 120 disposed concentric with the shaft of the main rotor 110 using the servo (not shown) in a manner that the swash plate 120 is tilted in a direction of an arrow b. In order to fly the helicopter in a upward direction (a direction of an arrow C) shown in FIG. 7(c), a right stick lever 101R of the radio control transmitter 100 is pushed upward to control the swash plate 120 disposed concentric with the shaft of the main rotor 110 using the servo (not shown) in a manner that the swash plate 120 is tilted in a direction of an arrow c.
As described above, while the model helicopter is remotely controlled by controlling the swash plate using the servo, controls for moving a fuselage in the forward, reverse, left, right, upward and downward directions are carried out in a combined manner. Therefore, the swash plate is subjected to the combination of the pitch control, the roll control and the collective pitch control.
However, the swash plate disposed concentric with the shaft of the main rotor has a limited maximum control range (maximum slant) at which a control range is maximum due to a mechanical limitation. Therefore, when the pitch control and the roll control perpendicular to each other are carried out simultaneously so that ranges of the pitch control and the roll control are added, a control range of the swash plate is saturated. When the control range of the swash plate is saturated, an excessive load is applied to the servo (the servo for controlling the roll or the pitch) which is an operating source thereof or to a linkage rod connecting the swash plate and the servo.
Therefore, the control range is required to be large because an immediate response of the roll control and the pitch control is necessary in the model helicopter performing an acrobatic flying (three dimensional flying).
Some of the transmitter employs a method wherein the control range of the swash plate is controlled by inserting a ring shape plate referred to as a stopper along an outer edge of the stick lever of the radio control transmitter for the model to mechanically limit the operation of the stick lever.
However, even when the saturation of the swash plate is solved by the stopper which is a mechanical means, a drawback described below still exists.
The controls of the pitch and the roll are carried out by one stick lever or by dividing into left and right stick levers. When the one stick lever is used, the stopper solves the problem. However, when the left and right stick levers are used, the stopper is not sufficient for a normal operation.